scholarly journals Thermal Conductivity Analysis of Chitin and Deacetylated-Chitin Nanofiber Films under Dry Conditions

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 658
Author(s):  
Jiahao Wang ◽  
Keitaro Kasuya ◽  
Hirotaka Koga ◽  
Masaya Nogi ◽  
Kojiro Uetani
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Adsorbed Water ◽  
Amino Groups ◽  
Accurate Analysis ◽  
Chitin Nanofiber ◽  
Natural Polysaccharide ◽  
Amino Group Content ◽  
Dry Conditions ◽  
The Difference

Chitin, a natural polysaccharide polymer, forms highly crystalline nanofibers and is expected to have sophisticated engineering applications. In particular, for development of next-generation heat-transfer and heat-insulating materials, analysis of the thermal conductivity is important, but the thermal conductivity properties of chitin nanofiber materials have not been reported. The thermal conductivity properties of chitin nanofiber materials are difficult to elucidate without excluding the effect of adsorbed water and analyzing the influence of surface amino groups. In this study, we aimed to accurately evaluate the thermal conductivity properties of chitin nanofiber films by changing the content of surface amino groups and measuring the thermal diffusivity under dry conditions. Chitin and deacetylated-chitin nanofiber films with surface deacetylation of 5.8% and 25.1% showed in-plane thermal conductivity of 0.82 and 0.73 W/mK, respectively. Taking into account that the films had similar crystalline structures and almost the same moisture contents, the difference in the thermal conductivity was concluded to only depend on the amino group content on the fiber surfaces. Our methodology for measuring the thermal diffusivity under conditioned humidity will pave the way for more accurate analysis of the thermal conductivity performance of hydrophilic materials.

scholarly journals Effects of heat sink compounds on contact resistance of porous media

2007 ◽  
Vol 11 (4) ◽  
pp. 113-124 ◽  
Author(s):  
Olukayode Akinyemi ◽  
Thomas Sauer
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Contact Resistance ◽  
Heat Sink ◽  
Thermal Probe ◽  
Dry Conditions ◽  
Thermal Grease ◽  
Water Contents

High and low-conductivity heat sink compounds were applied in succession on a thermal probe, which was then used to determine the thermal conductivity and thermal diffusivity of some porous media at room temperature. The experiment was conducted separately under different packing densities and water contents to see the effects of the heat sink compounds on the thermal properties at such conditions. High conductivity grease increased the values of thermal conductivity considerably and thus reduces the contact resistance, with increase in bulk density at air-dry conditions, but had virtually no effects on its thermal diffusivity. It however decreased both the thermal conductivity and thermal diffusivity with water content increment. The thermal properties obtained without thermal grease vary considerably from those with the heat sink compounds as water was being applied. The variation however reduced also considerably towards saturation.

Thermal Characterization of Carbon-Carbon Composites

2011 ◽  
Author(s):  
Messiha Saad ◽  
Darryl Baker ◽  
Rhys Reaves
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Carbon Composite ◽  
Flash Method ◽  
Carbon Composites ◽  
Energy Storage Devices ◽  
Graphitized Carbon

Thermal properties of materials such as specific heat, thermal diffusivity, and thermal conductivity are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells and solar cells. Thermal conductivity plays a critical role in the performance of materials in high temperature applications. Thermal conductivity is the property that determines the working temperature levels of the material, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this research is to develop thermal properties data base for carbon-carbon and graphitized carbon-carbon composite materials. The carbon-carbon composites tested were produced by the Resin Transfer Molding (RTM) process using T300 2-D carbon fabric and Primaset PT-30 cyanate ester. The graphitized carbon-carbon composite was heat treated to 2500°C. The flash method was used to measure the thermal diffusivity of the materials; this method is based on America Society for Testing and Materials, ASTM E1461 standard. In addition, the differential scanning calorimeter was used in accordance with the ASTM E1269 standard to determine the specific heat. The thermal conductivity was determined using the measured values of their thermal diffusivity, specific heat, and the density of the materials.

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